Safety feature for door latch



June 15, 1965 c. GETMAN 3,189,375

SAFETY FEATURE FOR DOOR LATCH Filed May 1, 1963 2 Sheets-Sheet l J INVENTOR.

CLARENCE GETMAN H s ATTORNEY June 15, 1965 c. GETMAN 3,189,375

SAFETY FEATURE FOR DOOR LATCH Filed May 1, 1963 2 Sheets-Sheet 2 Q Q\ INVENTOR. j\ cumszncs. QETMAN \\\\\\\\\\Q\ BY I g- 2.! \3 3 Hus ATTORNEY United States Patent 0 3,18%,375 SAFETY FEATURE EUR DUGR LATCH liar-once German, Fern Creek, Ky, assignor to General Electric Qompany, a corporation of New Yuri: Filed May l, 1963, Ser. No. 277,174 6 Claims. (Cl. Lidia-di The present invention relates to a door latch mechanism for holding a door in a tightly locked position. Such doors are sometimes referred to as the self-sea1ing type; i.c., doors having latches which are so designed that during the final stages of their closing movement they compress a door gasket.

This invention was conceived as an improvement over the door latch mechanism of the copending application of Ray C. Eigelbach application Serial No. 135,876, now Patent No. 3,125,365, which was filed on September 5, 1961, and is assigned to the General Electric Company the assignee of the present invention. Both of these door latch mechanisms were developed for use with a high temperature oven for domestic use where the oven has provision for an automatic heat cleaning cycle and the temperature is raised to between 750 F. and 950 P. so as to burn off all food soil from the oven Walls. In such a high temperature oven it is imperative to latch the door before the cleaning cycle is set in motion so that the door will not be open during the heat cleaning cycle. It i likewise important to seal the door so as to preclude the escape of smoke, odors, and heat from around the door while the'food soil is being removed from the oven liner walls by a process of pyrolysis. If it were possible to open the door while the oven was operating at one of these elevated heat cleaning temperatures, there would be an excess of oxygen within the oven cavity to combine with the hot greases and this might cause a sudden high flame which could be harmful. oven controls have been devised for such an oven so that the heat cleaning cycle cannot be initiated until the door latch mechanism has clamped the door into a sealed position, and the door cannot be reopened until the temperature within the oven drops to an amount below the maximum normal cooking temperatures or" about 550 F.

The primary object of the present invention is to provide a simplified door latch mechanism having a minimum number of parts where the mechanism is provided with a door sensing means to insure that the door latch mechanism cannot be closed if the door is not first present in its closed position.

A further object of the present invention is to provide a door latching mechanism of the class described where both the latching bolt and the keeper are out of sight when the latch mechanism is not being used a during normal cooking operations.

A further object of the present invention is to provide a door latching mechanism that will return to its unlocked position once manual control is released from the latch in the event the mechanism did not reach its fully locked position. i

A still further object of the present invention is to provide a door latch mechanism with a swinging handle lover, a latching bolt pivotally joined to the handle lever and a door sensing bar carried by the latching bolt and cooperating With a stop means to insure that the latching mechanism cannot be closed if the door is not first present in its closed position.

The present invention, in accordance with one form thereof, is embodied in a door latch mechanism that is mounted within a door frame adjacent the distal edge. of the door. The latch mechanism is provided with a mounting bracket to which is pivotally mounted a latching bolt that is adapted to engage and disengage the door to be locked. A handle lever is also pivotally mounted Accordingly, door latches and i so that the latching bolt cannot engage the door WllllOllll,

the door sensor bar being deflected. If the latching mechanism is moved from its open position toward its closed position and the door has not first been closed, the door sensor bar will meet an obstruction in the form of stop means in the path of its movement thereby preventing the latching bolt from completing its movement toward its closed position.

My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a right side elevational view of a freestanding range having a door latch mechanism embodying the present invention;

FIGURE 2 is a fragmentary plan view partly in crosssection on an enlarged scale taken along line 2-2 of FIG- URE 1 and showing the latch mechanism in its open position disengaged from the oven door, which would be the position of the latch mechanism during normal cooking operations;

FIGURE 3 is a fragmentary elevational view taken on the line 3-3 of FIGURE 2;

FIGURE 4 is a fragmentary plan view showing only the manner of pivotally mounting the latching bolt to the mounting bracket with the bolt appearing in its open position;

FIGURE 5 is a fragmentary plan viewsimilar to that of FIGURE 2 illustrating the situation when the door is left open and the handle lever has been moved toward its closed position until an interference occurs to prevent the completion of the action;

FIGURE 6 is a fragmentary plan view of the latch mechanism comparable to that of FIGURE 5 showing the oven door in the closed position and the latch mechanism moved to its fully closed position.

Turning now to a consideration of the drawings and in particular to FIGURE 1 there is shown for illustrative purposes a free-stanuing electric range it) having atop cooking surface 11 with a plurality of surface heating elements 12, an oven cavity 13, a front-opening oven door 14, and a backsplashcr 15 arranged along the back edge of the cooking surface 11 and containing a control panel (not shown) having. control components which govern the energization of the various heating elements of the range. The oven cavity 13 includes the two standard electric heating elements; namely, a lower bake unit l6 arranged just above the bottom of the oven cavity and an upper broil unit 17 which is located just under the top wall of the oven cavity.

The latch mechanism of the present invention is indicated by the numeral 2% and it is located within the oven cabinet or range body above the door opening. As mentioncd previously this invention of a novel latch mechanism 2% has been found of primary importance when used with a high temperature heat cleaning oven. In such an oven there is a third heating element or mullion heater 21 as seen in FIGURE 3 that is located near the front door opening of the open cavity to encircle the oven liner and compensate for the loss of heat through and around the door opening. It is a type of heating element that has a helical resistance wire encased in a high te1nperature insulating material such as magnesium oxide, and which in turn is covered with a metal sheath or jacket as is standard heating element construction in this art.

There is a decided advantage in designing an oven door latch mechanism to be mounted in the range body or door frame rather than in the door structure. Whenthe latch mechanism is in the range body it can be mounted above the oven insulation 22 so that it is somewhat protected from the high temperature of the oven liner 23 which forms with the oven door 14 the oven cavity 13. The oven door is relatively thin and would provide little heat protection for the latch as compared with the available insulated space under the cooktop Ill. It is recognized that in other applications such as drop-door auto matic dishwashers, the parts could be reversed so as to locate the latch mechanism in the door without departing from the spirit of the present invention.

The latch mechanism is perhaps best shown in FIGURE 2 as comprising a mounting bracket 25 which is a generally flat sheet metal member with an upturned flange 26 along its front edge so that it may be screwed to the rear surface of the front wall of the range body. Next there is a vertically pivoted latching bolt 28 which is partially obscured in FIGURE 2 because it is carrying a door senser bar 29. The nature of the latching bolt 28 can best be understood by referring to FIGURE 4 which shows the bolt in the same position that it has taken in FIGURE 2 but with the door senser bar 29 removed. The latching bolt 28 swings in a horizontal plane by being pivotally mounted on the mounting bracket 25 by a pin and slot connection such as the fixed pin 3% on the bracket and the elongated slot 31 in the latching bolt that extends longitudinally thereof. The forward end of the latching bolt 28 has a hook portion 32 which is adapted to engage a keeper 33 on the oven door 14. The front wall of the range body has an elongated horizontal slot 34 for receiving the latching bolt 28 therethrough, and the oven door 14 has a related slot 35 formed in its inner door liner. The door is hollow in the vicinity of this slot 355 to permit the hook portion 32 of the latching bolt to extend into the interior of the door and engage around the side edge or keeper 33 of the slot 35. A modified door design uses a cantilever spring Within the door for engagement by the hook 32 so as to compensate for manufacturing tolerances and to be able to utilize a more rigid gasket construction than the one shown as element 53.

It should be noted that the latching bolt 28 in the open position of the latch mechanism in FIGURE 2 is completely Withdrawn into the range body or door frame. In addition the keeper 33 on the door does not present any protrusion or obstruction on the inner facing of the door. This is important from an appearance as well as a. functional point of view in that there are no obstructions or projections on which clothing may be caught or arms scratched by striking such appurtenances. Another advantage for recessing the latch mechanism Within the door frame is that its structure is hidden which beclouds a knowledge of its construction, and this lack of information tends to discourage the unauthorized manipulation of the mechanism if a person were to make an attempt to fool the mechanism and operate it in an unsafe manner.

The rearward portion of the mounting bracket 25 has a channel formation 3'7 shown as resting on its side as seen in FIGURE 3 with a vertical end wall 38 and a horizontal overlapping flange 39. The principal reason for this channel formation 3'? is to provide a pivot means for a handle lever 42;. The innermost end of the handle lever 42 also has a channel formation 43 with two parallel horizontal walls 44 and 45 that are joined together by a vertical wall 46 that is mostly cut-away in FIGURE 3. Accordingly, the channel member 43 of the handle lever 42 fits snugly into the channel member 37 of the mounting bracket and is pivoted thereto by a pair of pivot pins 47 and 48 which are understandably located on a common vertical axis so that the hinge lever 42 may pivot within a horizontal plane through an angle of about 60 from a first open position shown in FIGURE 2 to a second fully closed position of FIGURE 6. The front wall of the range body has a horizontal slot so that the outermost end of the handle lever 42 may protrude therethrough for manual manipulation.

Next is needed a pivotal connection between the handle lever 4-2 and the innermost end of the latching bolt 23. This connection is provided by a pin and slot or cam follower connection best seen in FIGURE 6 in the form of a vertical pin Silt carried by the latching bolt 28 that is captured within a cam-shaped slot 51 formed in the lower wall of the channel end 43 of the handle lever 42. In other words, this type of pivotal connection constitutes a cam follower connection between the handle lever 42 and the latching bolt 28. The cam slot 51 is so shaped that it pivots the latching bolt 28 in a counterclockwise direction as seen in FIGURE 6 when the latch mechanism is being opened, and in a clockwise direction when the mechanism is being closed. Moreover, the cam slot 51 serves to pull the latching bolt 22 in a rearward direction away from the door once the latching bolt 28 has engaged the keeper 33 of the door. The purpose of this is as mentioned earlier to clamp the door'tightly sealed against a door gasket such as elements 53 and 53' shown in FIGURE 3.

The proper turning action of the latching bolt 2d is also controlled by a second cam slot 55 which is best shown in FIGURE 4 as being of generally sock shape with a straight ankle portion 55 and a foot shaped portion 57. The purpose of the foot shaped portion 5'7 is to pivot the latching bolt 28 from its unlocked retracted position of FIGURE 4 to its fully extended position of FIGURE 5, while the straight portion as of the cam slot 55 permits the cam slot 51 of the handle lever 32 to withdraw the latching bolt 23 a slight amount into the range body thereby tightly clamping the door closed into the position shown in FIGURE 6. The pin has an upper end cooperating with the slot 51 in the handle lever 4-2 and a lower end beneath the latching bolt 28 to cooperate with the slot in the mounting bracket 25.

Combined with this latch mechanism 2d but not shown is an electric control circuit means which is activated only when the latch mechanism is in its fully locked position. This electric circuit means controls the heat cleaning circuit for the oven so that it is not possible to raise the oven temperature into the heat cleaning temperature range of between 750 and 950 F. unless the latch mechanism 2% is fully closed. One modification would utilize an electric switch that would be actuated by the door senser bar 29 once the bar is deflected by the door keeper 33. With such a switch a person could not energize the heat cleaning cycle by manually moving the senser bar because once the hand is removed the senser bar disengages the switch as will be explained hereinafter. It is imperative to insure that the oven door 14 is closed before the latch mechanism can be closed to activate the heat cleaning cycle. Hence, the latch mechanism includes the door senser bar 2? which overlies the latching bolt 23 and is pivotally mounted thereto adjacent its midportion by means of a vertical pin 60. The upper portion of this pin on is enlarged to support a torsion spring 61 that normally biases the door senser bar 29 to overlie the hook portion 32 of the latching bolt 28 as is best seen in FIGURES 2 and 5. The latch mechanism includes a stop means in the form of a vertical post 63- joining the top and bottom walls 44 and 45 of the channel end formation 43 of the handle lever 42 as is best seen in FIGURE 3. This post serves a dual function of cooperating with the door senser bar 29 as well as serving as an attaching point for an overcenter spring 64 that is connected at one end to the post 63 and at its other end to the vertical wall 38 of the channel formation 37 of the mounting bracket 25 as will be explained further hereinafter.

Now for an explanation of the operation, attention is directed to the plan view of FIGURE 5. It should first be recognized that the oven door 114 is not present in its closed position. The handle lever 42, has been moved to an intermediate position between the unlocked and the locked positions of FIGURES 2 and 6 respectively, but this is as far as the latch mechanism will move, The latching bolt 28 is shown in an extended position from the range body, but since the oven door is not in place the door sensor bar 29 is unmoved and it retains the same relative position with respect to the latching bolt 28 as it had in the unlocked position of FIGURE 2 due to the action of the torsion spring at. Accordingly, you will note in FIGURE 5 that the innermost end 55 of the door senser bar 29 is directly opposed by the vertical post or stop means 63. It is also clear in FIGURE 5 that the tension spring 64 has not passed through the vertical axis of the handle lever 42 that is defined by the pivot pins 47 and 48. Accordingly, when manual control is released from the handle lever in the situation of FIG- URE- 5, the tension spring 64 will contract to return the latch mechanism back to its unlatc'hed position of FIG- URE 2. The tension spring he also tends to swing the latch mechanism to its locked posit-ion of FIGURE 6 as soon as the longitudinal axis of the spring moves past the vertical pivotal axis or" the handle lever 42. Now compare FiGURE 5 with the showing in FEGURE 6 wherein the oven door 14 is in its closed position and you will notice that the keeper 33 has been engaged by the hook port-ion 32 of the latching bolt 28 and simultaneously the door senser bar 29 has been deflected in a counterclockwise direction through an angle of about 15 against the bias of the torsion spring 61. This angular deflection is just enough to move the innermost end 65 of the door senser bar out of interference with the stop means 63 so that the handle lever 42 may be moved to its fully locked position.

Having described above my invention of a door latch mechanism for an appliance such as an oven of a domestic rangeit will readily be apparent to those skilled in this art that such a lat-ch mechanism would have general utility in other arts such as in a drop-door dishwasher and also for the door of a microwave oven where instead of or in addition to the radiant heating elements 16 and 1'7 there would be the provision of microwave energy for increasing the speed of cooking. In such an oven it would also be imperative to tightly seal the door against a suitable gasket to prevent the leakage of the microwave energy.

Modifications of this invention will occur to those skilled in this ant, therefore, it is to be understood that this invent-ion is not limited to the particular embodiments disclosed but that it is intended .to cover all modifications which are within the true spirit and scope of this invention as claimed.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A latch mechanism adapted for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a mounting bracket which is supported from the door frame adjacent the distal edge of the door, a latching bolt pivotally mounted on said bracket and having a hook portion on the tree end thereof, the door including a keeper for mating engagement with the hook portion of the latching bolt, a handle lever pivotally mounted to the said bracket and pivotally connected to the latching bolt so that swinging action of the handle lever causes a swinging movement in the bolt, a door senser bar pivotally supported on the latching bolt, and spring means acting upon the door senser bar to cause a portion of it to overlie the hook portion of the latching bolt, the latch mechanism including a stop means so that if the handle lever is caused to move from its open position towards closed position and the door is not in its closed position a portion of the door senser bar will normally engage the stop means and restrict the movement of the handle lever at a point intermediate its full range of travel.

2. A cabinet provided with an access opening and ahinged door for closing the opening, a latch mechanism supported in the cabinet for locking the door in the closed position, the latch mechanism comprising a mounting bracket with a latching bolt pivotally mounted adjacent the midportion of the bolt, one end of the latching bolt having a hook portion, a keeper for-med on the door for engagement by the hook portion of the latching bolt, a handle lever pivotally mounted at one end to the bracket, an intermediate portion of the handle lever having a connection with the end of the latching bolt thatis opposite the said hook portion, and means cooperating with the latching bolt for sensing the presence of the door while the handle lever is being moved from a first openposition, said sensing means comprising a door senser bar pivotally supported on the latching bolt, and spring means acting upon the door senser bar to cause a portion of it t0 overlie the hook portions of the latching bolt, and stop means located on the latch mechanism and cooperating with the door senser bar to prevent the full movement of the handle lever from the open to the closed position if the door is not first closed so that the door is able to engage the door senser bar as the latching bolt swings out to engage the keeper of the door.

3. A cabinet provided with an access opening and a door for closing the opening, a latch mechanism supported in the cabinet for locking the door in a closed position, the latch mechanism comprising a mounting bracket with a latching bolt pivotally mounted to the bracket with a pin and slot connection, one end of the latching bolt having a hook portion, a keeper formed on the door for engagement by the latching bolt, a handle lever pivotally mounted to the bracket and having a pin and slot connection to the latching bolt, the handle lever being mova'ble between a first open position and a second closed position, the latching bolt in the open position of the mechanism being completely withdrawn into the cabinet, the latching bolt in the closed position of the mechanism extending outwardly of the cabinet and substantially perpendicular thereto, and means for sensing the presence of the door in the closed position when the handle lever is being moved between its open position and its closed position, said means including a door senser bar carried by the latching bolt and cooperating with the hook portion thereof, and stop means provided on the handle lever to be in the path of movement of the door senser bar as the handle lever is moved to the closed position and the door is open, while if the door is closed the senser bar will be shifted to bypass the stop mean-s during the movement of the handle lever;

t. An appliance cabinet provided with a front opening and a hinged door for closing the opening, a latch mechanism supported in the cabinet above the door opening for locking the door in the closed position, the latch mechanism comprising a mounting bracket with a latching bolt pivotally mounted to the bracket with a pin and slot connection to swing in a generally horizontal plane, a slot formed in the front of the cabinet adjacent the latching bolt, the latching bolt being completely retracted into the cabinet in one position and extending through the slot in a second position to lie generally perpendicular to the cabinet, a keeper recessed Within the door for engagement by the latching bolt, a handle lever having one end pivotally mounted to the bracket, an intermediate portion of the handle lever having a connection to the end of the latching bolt to cause the latching bolt to shift away from the door and slightly back into the cabinet once the bolt engages the door keeper so as to clamp the door tightly shut, a second slot formed in the front wall of the cabinet for accommodating the opposite end of the handle lever for manual operation, a stop means provided on the handle lever, and a door senser bar cooperating with the latching bolt and the stop means to disable the latching V mechanism if the door is not in a closed position when the latching mechanism is being operated, said door senser bar being disabled by the door keeper when the door is in its closed position, and overcenter spring means acting upon the handle lever to normally retain the lever in one of its two extreme positions when manual control is released therefrom.

5. A latch mechanism adapted for locking a door, a door and a door frame where the door is hingedly mounted to the door frame along one edge thereof, said latch mechanism having a mounting bracket which is supported within the door frame adajacent the distal edge of the door, a latching bolt with a hook portion on the free end thereof that is pivotally mounted on said bracket to swing in a plane generally parallel with the distal edge of the door, the door having a keeper for engagement by the latching bolt, ahandle lever having one end pivotally mounted to the bracket, an intermediate portion of the handle lever being joined to an end portion of the latching bolt for pivotal movement therebetween, a door senser bar pivotally supported from the latching bolt, and spring means acting upon the door senser bar to cause a portion of it to normally overlie at least pait of the hook portion of the latching bolt, and stop means located on the handle lever and serving in one situation as an obstruction to the movement of the door senser bar and hence the latching bolt if the door senser bar is not deflected by the presence of the door in its closed position, the stop means in a second situation being bypassed by the door senser bar when the latching bolt is engaging the door keeper thus deflecting the door senser bar out of position against the bias of said spring.

6. A cabinet provided with a door frame defining an access opening and a door for closing the opening, a latch mechanism supported on one of the door and door frame members, a keeper supported on the member opposite the latch supporting member, the latch mechanism comprising a mounting bracket with a latching bolt pivotally mounted to the bracket with a cam follower connection, one end of the latching bolt having a hook portion for engagement with the keeper, a handle lever pivotally mounted to the bracket and having a lost motion connection with the latching bolt, the handle lever being movable between a first open position and a second closed position, the latching bolt in the open position of the mechanism being substantially within the mechanism support member, and means for sensing the presence of the door in the closed position when the handle lever is being moved between its open position and its closed position, said means including a door senser bar cairied by the latching bolt and cooperating with the hook portion thereof, and stop means provided on the mechanism to be in the path of movement of the door senser bar as the handle lever is moved to the closed position and the door is open so as to obstruct the full closing of the latchmechanism, While if the door is closed the keeper will deflect the senser bar and the bar will bypass the stop means so that the latch mechanism can be fully closed.

References Cited by the Examiner UNITED STATES PATENTS 510,686 12/93 Hood 292-411 2,738,211 3/56 Schlueter 292-1ll 3,005,065 10/61 Jellies 200-61.62

M. HENSON WOOD, 111., Primary Examiner.

THOMAS J. HICKEY, Examiner. 

1. A LATCH MECHANISM ADAPTED FOR LOCKING A DOOR, A DOOR AND A DOOR FRAME WHERE THE DOOR IS HINGEDLY MOUNTED TO THE DOOR FRAME ALONG ONE EDGE THEREOF, SAID LATCH MECHANISM HAVING A MOUNTING BRACKET WHICH IS SUPPORTED FROM THE DOOR FRAME ADJACENT THE DISTAL EDGE OF THE DOOR, A LATCHING BOLT PIVOTALLY MOUNTED ON SAID BRACKET AND HAVING A HOOK PORTION ON THE FREE END THEREOF, THE DOOR INCLUDING A KEEPER FOR MATING ENGAGEMENT WITH THE HOOK PORTION OF THE LATCHING BOLT, A HANDLE LEVER PIVOTALLY MOUNTED TO THE SAID BRACKET AND PIVOTALLY CONNECTED TO THE LATCHING BOLT SO THAT SWINGING ACTION OF THE HANDLE LEVE CAUSES A SWINGING MOVEMENT IN THE BOLT, A DOOR SENSER BAR PIVOTALLY SUPPORTED ON THE LATCHING BOLT, AND SPRING MEANS ACTING UPON THE DOOR SENSER BAR TO CAUSE A PORTION OF IT TO OVERLIE THE HOOK PORTION OF THE LATCHING BOLT, THE LATCH MECHANISM INCLUDING A STOP MEANS SO THAT IF THE HANDLE LEVER IS CAUSED TO MOVE FROM ITS OPEN POSITION TOWARDS ITS CLOSED POSITION AND THE DOOR IS NOT IN ITS CLOSED POSITION A PORTION OF THE DOOR SENSER BAR WILL NORMALLY ENGAGE THE STOP MEANS AND RESTRICT THE MOVEMENT OF THE HANDLE LEVER AT A POINT INTERMEDIATE ITS FULL RANGE OF TRAVEL. 